org.springframework.beans.NotReadablePropertyException: Invalid property 'principal.username' of bean class [org.springframework.security.authentication.UsernamePasswordAuthenticationToken]: Bean property 'principal.username' is not readable or has an invalid getter method: Does the return type of the getter match the parameter type of the setter?

org.springframework.beans.NotReadablePropertyException: Invalid property 'login' of bean class [springapp.service.LoginValidator]: Bean property 'login' is not readable or has an invalid getter method: Does the return type of the getter match the parameter type of the setter?

org.springframework.beans.NotReadablePropertyException: Invalid property 'email' of bean class [org.graylog2.restclient.models.api.requests.CreateUserRequestForm]: Bean property 'email' is not readable or has an invalid getter method: Does the return type of the getter match the parameter type of the setter?

Root Cause Analysis

org.springframework.beans.NotReadablePropertyException

Invalid property 'earlyCancellation.deadlines[0]' of bean class [com.despegar.bookedia.cancelpolicy.CancelPolicyDTO]: Bean property 'earlyCancellation.deadlines[0]' is not readable or has an invalid getter method: Does the return type of the getter match the parameter type of the setter?